diff --git a/CHANGELOG.md b/CHANGELOG.md
index 895b8a95..39779d5a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,9 @@
 # Change Log
+## [5.52.4](https://github.com/plivo/plivo-dotnet/tree/v5.52.4) (2026-07-27)
+**Feature - Endpoint internal flag support**
+- Added optional `isInternal` (bool?) parameter to Endpoint `Create` and `CreateAsync` methods, sent as `internal` on the wire, to mark newly created SIP endpoints as internal at creation time
+- C# reserved-keyword workaround: parameter is named `isInternal` because `internal` is a C# keyword; the outgoing JSON key is still `internal`
+
 ## [5.52.2](https://github.com/plivo/plivo-dotnet/tree/v5.52.2) (2026-06-11)
 **Feature - PhoneNumber Buy compliance application support**
 - Added optional `complianceApplicationId` parameter to PhoneNumber `Buy` and `BuyAsync` methods, sent as `compliance_application_id`, to link a regulatory compliance application at purchase time for regulated numbers
diff --git a/src/Plivo/Plivo.csproj b/src/Plivo/Plivo.csproj
index d4272717..51a4fd7c 100644
--- a/src/Plivo/Plivo.csproj
+++ b/src/Plivo/Plivo.csproj
@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>netstandard2.0;netstandard1.3</TargetFrameworks>
-    <ReleaseVersion>5.52.2</ReleaseVersion>
+    <ReleaseVersion>5.52.4</ReleaseVersion>
     <Version />
     <Authors>Plivo SDKs Team</Authors>
     <Owners>Plivo Inc.</Owners>
diff --git a/src/Plivo/Plivo.nuspec b/src/Plivo/Plivo.nuspec
index 7b34b717..d01e280e 100644
--- a/src/Plivo/Plivo.nuspec
+++ b/src/Plivo/Plivo.nuspec
@@ -4,7 +4,7 @@
     <summary>A .NET SDK to make voice calls and send SMS using Plivo and to generate Plivo XML</summary>
     <description>A .NET SDK to make voice calls and send SMS using Plivo and to generate Plivo XML</description>
     <id>Plivo</id>
-    <version>5.52.2</version>
+    <version>5.52.4</version>
     <title>Plivo</title>
     <authors>Plivo SDKs Team</authors>
     <owners>Plivo, Inc.</owners>
diff --git a/src/Plivo/Resource/Endpoint/EndpointInterface.cs b/src/Plivo/Resource/Endpoint/EndpointInterface.cs
index 8c0117e4..4ec570b9 100755
--- a/src/Plivo/Resource/Endpoint/EndpointInterface.cs
+++ b/src/Plivo/Resource/Endpoint/EndpointInterface.cs
@@ -32,8 +32,10 @@ public EndpointInterface(HttpClient client) : base(client)
         /// <param name="password">Password.</param>
         /// <param name="alias">Alias.</param>
         /// <param name="appId">App identifier.</param>
+        /// <param name="isInternal">Optional flag to mark the endpoint as internal. Serialized as <c>internal</c> on the wire (the C# keyword <c>internal</c> cannot be used as a parameter name).</param>
         public EndpointCreateResponse Create(
-            string username, string password, string alias, string appId = null)
+            string username, string password, string alias, string appId = null,
+            bool? isInternal = null)
         {
             var mandatoryParams = new List<string> { "" };
             bool isVoiceRequest = true;
@@ -47,6 +49,9 @@ public EndpointCreateResponse Create(
                     appId,
                     isVoiceRequest
                 });
+            if (isInternal.HasValue) {
+                data["internal"] = isInternal.Value;
+            }
 
             return ExecuteWithExceptionUnwrap(() =>
             {
@@ -66,9 +71,11 @@ public EndpointCreateResponse Create(
         /// <param name="appId">App identifier.</param>
         /// <param name="callbackUrl">Callback URL.</param>
         /// <param name="callbackMethod">Callback Method.</param>
+        /// <param name="isInternal">Optional flag to mark the endpoint as internal. Serialized as <c>internal</c> on the wire (the C# keyword <c>internal</c> cannot be used as a parameter name).</param>
         public async Task<AsyncResponse> CreateAsync(
             string username, string password, string alias, string appId = null,
-            string callbackUrl = null, string callbackMethod = null)
+            string callbackUrl = null, string callbackMethod = null,
+            bool? isInternal = null)
         {
             MpcUtils.ValidUrl("callbackUrl", callbackUrl, true);
             var mandatoryParams = new List<string> { "" };
@@ -88,6 +95,9 @@ public async Task<AsyncResponse> CreateAsync(
             if (data.ContainsKey("callback_method") && callbackMethod == null) {
                 data.Remove("callback_method");
             }
+            if (isInternal.HasValue) {
+                data["internal"] = isInternal.Value;
+            }
             var result = Task.Run(async () => await Client.Update<AsyncResponse>(Uri, data).ConfigureAwait(false)).Result;
             await Task.WhenAll();
             result.Object.StatusCode = result.StatusCode;
diff --git a/version.json b/version.json
index 8b3cda3b..8c0c1972 100644
--- a/version.json
+++ b/version.json
@@ -1,5 +1,5 @@
 {
-  "version": "5.52.2",
+  "version": "5.52.4",
   "publicReleaseRefSpec": [
     "^refs/heads/master$",
     "^refs/heads/v\\d+(?:\\.\\d+)?$"